1. Field of the Invention
The present invention relates to a chuck for a hand-held power tool, in particular, for a diamond drilling tool. The chuck is connected with the spindle of the hand-held power tool for joint rotation therewith. The chuck comprises a locking device for securing a shaft section of an exchangeable working tool having a circular cross-section, without a possibility of axial displacement and rotation relative to the chuck.
2. Description of the Prior Art
A chuck, which is described above, is suitable for using working tools the shaft of which has a cylindrical form. Thereby, a hand-held power tool can be used with commercially available working tools such as, i.e., drill bits and, in particular, diamond drills. The working tools, which are used with the hand-held power tools, can be produced, because of the simple form of their shafts, with relatively low manufacturing costs.
International publication WO96/35535 discloses a quick-action chuck in which a working tool can be secured against both axial displacement and rotation relative to the chuck. The quick-action chuck has a locking element having a plurality of locking rollers which are held in respective recesses of a carrier sleeve. The carrier sleeve is arranged within an actuation sleeve that forms, in its inner surface, a plurality of ramp regions for respective locking rollers. Upon rotation of the actuation sleeve relative to the carrier sleeve, the ramp sections press the locking rollers partially out of their respective recesses and into a longitudinal bore of the carrier sleeve. The pressed-out clamping rollers clamp the shaft of the working tool which was pushed into the longitudinal bore. In order to retain the clamping rollers in the clamping position, the actuation sleeve is secured on the carrier sleeve formlockingly or frictionally. frictionally.
The advantage of the known quick-action chuck consists in that the clamping element is used for both transmission of the rotational movement and axially securing the working tool. The axial locking takes place independent of whether the chuck is rotated or remains stationary.
The drawback of the known chuck consists in a relatively complex construction of the chuck which results, in particular, from a need to insure that the actuation sleeve is reliably secured on the carrier sleeve. As a result, the chuck is susceptible to failure, on one hand, and on the other hand, can be produced only with high manufacturing costs. Moreover, because of a predetermined position of the actuation sleeve relative to the carrier sleeve in the locking position only a shaft section having a predetermined diameter can be secured in the chuck. Furthermore, a relatively large force and expenditure of time is required for securing of the actuation sleeve on the carrier sleeve.
Accordingly, an object of the present invention is to provide a quick-action chuck for receiving a shaft section having a circular cross-section and in which the foregoing drawbacks are eliminated.
Another object of the present invention is to provide a quick-action chuck that would insure a rapid insertion and withdrawal of a working tool while insuring that the working tool is reliably secured in the chuck without any possibility of axial displacement and rotation relative to the chuck.